The present application relates to laboratory apparatus for the dyeing of textiles and more particularly relates to such apparatus for use where it is desired to introduce dye and/or chemicals into the bath in a controlled manner.
Dyers of textile fabrics routinely perform small scale dyeings to determine the commercial viability of processes using particular dyes or combinations of dyes with certain fabrics and for shade matching, e.g., determining the amount of dye needed to obtain a desired shade. Various laboratory apparatus are known for such small scale dyeings. One type of such apparatus uses a generally cylindrical vessel containing a liquid dyeing bath and a sample holder for moving the samples in the bath in a cyclical fashion such as with a twist and stroke motion. The sample holder typically includes a generally vertical rod connected to an overhead stirrer. Forks or a basket of wire or other perforated material mounted on the rod are typically provided to hold the sample so that it is carried with the sample holder.
Known apparatus of this type is effective in performing conventional dyeing processes where the dye and chemicals such as dyeing auxiliaries are present in the bath when the dyeing is begun. However, such apparatus has been found to be unsatisfactory for laboratory dyeings in which it is desired to add dye and/or chemicals in a controlled manner as the dyeing progresses. For example, with conventional apparatus, it is difficult to achieve a level dyeing of nylon fabrics if dye is added to a heated bath in a process such as that disclosed in PCT Publication No. WO92/08838, May 29, 1992.